X.org (xserver-xorg-core) transitioning from 1.14.5 to 1.15...... the X.org maintainers kind of announced that (without a fixed date) about a week or two ago ,,,, all xserver-xorg-video-* and xserver-xorg-input-* will need to be rebuilt against xserver-xorg-core 1.15.0

The advice is::: read what is to be be removed, and if Xorg packages are to to be removed and not being replaced, DO NOT ACTION the dist-upgrade.

Unless you do use "xserver-xorg-video-qxl" (virtual graphics, used for qemu(-kvm) and remote X (virtual and native), it is safe - but given that xserver-xorg-video-qxl is still FTBS on i386, the transition technically isn't over yet.